You are looking at a new , boxed Millett Colt Combat  White Outline Low Profile  Adjustable Rear Sight .

This sight is meant to be a fit on Colt  1911 ,and  all Colt variants except Gold Cups . It can also be fitted to most of the many Colt clones .

To fit properly you will need a competent gunsmith , or have acess to a machine shop as the slide requires milling and a new dovetail .

It will fit many other handguns if you have the machinery required to modify the slide and cut new dovetails .

To qualify for lower postal rates the box may be folded flat when it is shipped out